This invention pertains to methods for etching a workpiece. This invention also pertains to reactive ion etching.
Burnishing heads are typically used to burnish magnetic disks and/or disk substrates. Such heads are typically made of Al2O3—TiC (also known in the industry as AlTiC). The burnishing surfaces of burnishing heads are machined to leave a set of burnishing structures thereon to facilitate burnishing. The shape and profile of those structures are designed to optimize performance.
Although it is possible to make burnishing heads with some types of burnishing structures using a machining process, machining is difficult or impractical for other structure shapes. Accordingly, I have investigated forming a burnishing surface by selectively etching burnishing head substrate material using a RIE (reactive ion etching) process.
In one burnishing head design, it was discovered that the structures on the burnishing surface should be fairly tall (e.g. about 65 μm tall) and have substantially vertical walls. This is very difficult to achieve with a RIE process.
U.S. Pat. No. 6,296,776, issued to Sasaki, discusses using reactive ion etching to etch AlTiC. However, Sasaki does not achieve vertical walls when etching AlTiC.
U.S. Pat. No. 6,001,268, issued to Nguyen, discusses patterning a slider comprising alumina and TiC. Nguyen etches to shallow depths, e.g. on the order of 5 μm. See also Nguyen et al., “The Role of Inert Gases in Reactive Ion Etching of Al2O3—TiC (N58) Mixed Phases for Slider Air Bearing Surface Patterning”, ElectroChemical Society Proceedings Vol. 98-20 (1998).
Fukushima et al., “High-Rate and Smooth Surface Etching of Al2O3—TiC Employing Inductively Coupled Plasma (IPC)”, Jpn. J. Appl. Phys., Vol. 33 (1996), also discusses shallow etching of discusses etching Al2O3—TiC (e.g. 5.5 μm). See also Fukushima et al., “New Reactive Ion Etching for HDD Slider Fabrication”, IEEE Trans. Mag. Vol. 32, No. 5 (September, 1996)